/*
 * Copyright (c) 2022 Huawei Device Co., Ltd.
 * Licensed under the Apache License,Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/***
* 加密 base64encode(utf16to8(str))
* 解密 utf8to16(base64decode(str))
*/
export default class Base64 {
  static base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  static base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);

   /**
 * base64编码
 * @param {Object} str
 */
  static base64encode(str){
    var out, i, len;
    var c1, c2, c3;
    len = str.length;
    i = 0;
    out = "";
    while (i < len) {
      c1 = str.charCodeAt(i++) & 0xff;
      if (i == len) {
        out += this.base64EncodeChars.charAt(c1 >> 2);
        out += this.base64EncodeChars.charAt((c1 & 0x3) << 4);
        out += "==";
        break;
      }
      c2 = str.charCodeAt(i++);
      if (i == len) {
        out += this.base64EncodeChars.charAt(c1 >> 2);
        out += this.base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
        out += this.base64EncodeChars.charAt((c2 & 0xF) << 2);
        out += "=";
        break;
      }
      c3 = str.charCodeAt(i++);
      out += this.base64EncodeChars.charAt(c1 >> 2);
      out += this.base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
      out += this.base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
      out += this.base64EncodeChars.charAt(c3 & 0x3F);
    }
    return out;
  }
  /**
 * base64解码
 * @param {Object} str
 */
   static base64decode(str){
    var c1, c2, c3, c4;
    var i, len, out;
    len = str.length;
    i = 0;
    out = "";
    while (i < len) {
      /* c1 */
      do {
        c1 = this.base64DecodeChars[str.charCodeAt(i++) & 0xff];
      }
      while (i < len && c1 == -1);
      if (c1 == -1)
      break;
      /* c2 */
      do {
        c2 = this.base64DecodeChars[str.charCodeAt(i++) & 0xff];
      }
      while (i < len && c2 == -1);
      if (c2 == -1)
      break;
      out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
      /* c3 */
      do {
        c3 = str.charCodeAt(i++) & 0xff;
        if (c3 == 61)
        return out;
        c3 = this.base64DecodeChars[c3];
      }
      while (i < len && c3 == -1);
      if (c3 == -1)
      break;
      out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
      /* c4 */
      do {
        c4 = str.charCodeAt(i++) & 0xff;
        if (c4 == 61)
        return out;
        c4 = this.base64DecodeChars[c4];
      }
      while (i < len && c4 == -1);
      if (c4 == -1)
      break;
      out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
    }
    return out;
  }
  static utf16to8(str) {
    var out, i, len, c;
    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
      c = str.charCodeAt(i);
      if ((c >= 0x0001) && (c <= 0x007F)) {
        out += str.charAt(i);
      } else if (c > 0x07FF) {
        out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
        out += String.fromCharCode(0x80 | ((c >>　6) & 0x3F));
        out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
      } else {
        out += String.fromCharCode(0xC0 | ((c >>　6) & 0x1F));
        out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
      }
    }
    return out;
  }
   utf8to16(str) {
    var out, i, len, c;
    var char2, char3;
    out = "";
    len = str.length;
    i = 0;
    while(i < len) {
      c = str.charCodeAt(i++);
      switch(c >> 4)
      {
        case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
      // 0xxxxxxx
        out += str.charAt(i-1);
        break;
        case 12: case 13:
      // 110x xxxx　 10xx xxxx
        char2 = str.charCodeAt(i++);
        out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
        break;
        case 14:
        // 1110 xxxx　10xx xxxx　10xx xxxx
          char2 = str.charCodeAt(i++);
          char3 = str.charCodeAt(i++);
          out += String.fromCharCode(((c & 0x0F) << 12) |
          ((char2 & 0x3F) << 6) |
          ((char3 & 0x3F) << 0));
          break;
      }
    }
    return out;
  }
}
